1. Field of the Invention
This invention relates to a method and an agent for promoting the proliferation of intestinal bifidobacteria using isomalto-oligosaccharides as an active substance.
2. Discussion of Background
Bifidobacteria, which belong to the genus Bifidobacterium, are known to be useful microorganisms inhabiting the human intestines. They have an important role in maintaining human health by preventing the increase of microorganisms which produce harmful substances, such as amines and ammonia, in the intestines.
In general, sugars are known nutrients for bifidobacteria as well as for noxious microorganisms, and sugars which are utilized only by bifidobacteria are little known. Additionally, it cannot be presumed from the properties of a sugar, such as molecular structure, whether the sugar will be utilized selectively by bifidobacteria or not.
The bifidobacteria proliferating action of sugars such as lactulose, raffinose, stachyose is well-known. Lactulose has found practical use in food. However, these sugars are consumed not only by bifidobacteria but also by the microorganisms which produce harmful substances in the intestines.
The bifidobacteria proliferating action of palatinose, an isomer of sucrose, and of fructo-oligosaccharides which consist of one sucrose unit and from one to four fructose units is also known. They are reported as useful bifidobacteria proliferating agents since they are utilized selectively by the bifidobacteria (Japan Kokai Nos. 91193/1982 and 53834/1984).
The inventors have made the surprising discovery that isomalto-oligosaccharides exhibit selective bifidobacteria proliferating action.